Maybe I'm missing something, but I don't see the graphics card listed which is one of the most important components.
I have a Velocity Micro computer, which has been upgraded, as my business and gaming machine.
Check out this link to their $1500 gaming machine:
http://velocitymicro.com/wizard.php?iid=19
I would probably upgrade the graphics card to an 8800GT for an additional $65.
You also get:
1) USA based telephone support that not brain dead.
2) Beefy 500 Watt Power Supply
3) Multiple Fans (In & Out) for case cooling
4) All aluminum metal case
5) Lot and lots of customizable options.
6) Custom built and tested by a real person
7) SLI ready and lots of upgrade possibilities
At least for the moment, there is not much benefit to the quad for gaming with current games. That will change in the future.
Good luck.